1. FIELD OF THE INVENTION
The present invention relates to a beading structure for application to the edge of rigid sheets, such as a car door, for ornamental or protective purposes. More particularly, the present invention relates to a beading structure that is easy to mount, but is difficult to remove.
2. DESCRIPTION OF THE PRIOR ART
Prior art U-shaped channel type beading for protecting or decorating the edge of a panel, such as a metal sheet, a car door, and so forth, is known in the prior art. For example, U.S. Pat. No. 3,167,856, to Zoller, discloses a strip structure for protecting the edge of a metal structure, such as a car door, and includes clamping ribs or lifts that are deformed when the strip is pressed onto the edge of a panel, and which frictionally engage the panel to retain the strip thereon. The clamping ribs of Zoller, however, are too close to the opposite internal sidewall of the strip, and nearly touch the sidewall in the equlibrium position of the strip, causing significant interference with the panel edge and making it difficult to install. In all protective edge strips of this type, a strip that is too difficult to install, that is, one that requires more than about two pounds of force per linear inch, is, in practice, often not installed properly, leading to failure in the field. Furthermore, difficult installation often leads to excess deformation of the strip during installation, which permanently distorts the strip and reduces the force required to remove it, often causing the strip to fall off the edge it is installed on. Moreover, the limited gripping power of such a strip makes removal of the strip too easy, leading to an application that is not permanent, and may inadvertently disengage from the protected edge, even when it is properly installed.
U.S. Pat. No. 4,105,814 to Eggert discloses a U-shaped cross-section strip, having two spaced apart arms connected by a base, for protecting the edge of an automobile door or similar panel. Eggert discloses a number of embodiments, having inwardly projecting two-part tangs for retaining the strip on the protected surface. The structure of Eggert is, however, more complicated than required, which severely increases quality control expense and generally makes it more expensive to produce. Furthermore, Eggert does not conveniently allow symmetric beading. The strip of Eggert causes significant interference between the two-part tangs and the protected edge during installation, making the installation difficult and subject to the same shortcomings as Zoller. During removal, however, the auxiliary tang does not interact with the other tang, so the profile strip is not significantly more difficult to remove than it is to attach.
In many applications it is desired to install such beading or profile strip permanently. In addition, in many applications it is desirable that the strip present a symmetric appearance along the edge of the protected member. It is highly desirable that the strip be easy to apply, but difficult to remove. Furthermore, it is desirable that the strip can be removed without marring the material it is applied to.
Therefore, a significant need exists for a beading strip that presents a symmetric appearance, that is easy to apply, but difficult to remove, that can be removed without marring the material, but that is permanent unless intentionally removed.